Osazones, anhydrides

Osazone anhydrides have also been prepared by the deacetylation of the tetraacetates of n-galactose methylphenyl-phenylosazone and from... 

Fischer projections and, 977-978 glycosides of, 989-990 hemiacetals of, 984-986 osazones from, 1013 oxidation of, 992-994 phosphorylation of, 991 reaction with acetic anhydride, 988... 

Lactosone was first prepared by the hydrochloric acid decomposition of the phenylosazone,1 although it had been noted that, in acid solutions, lactose phenylosazone forms an anhydride.197 Since its discovery,17 the benzaldehyde method has usually been employed,6-10-28 because it avoids the risks of osone hydrolysis and of alteration to the osazone. Lactosone is hydrolyzed by hot, dilute, mineral acid to D-glucosone and D-galactose.1-6 It reacts with cyanide to form an analog of iminoascorbic acid which, on acid treatment, is converted into a mixture of D-glucoascorbic acid and D-galactose.10... 

Another type of substituted pyrazole is obtained by refluxing osazones with acetic anhydride during the acetylation, two molecules of water per molecule are removed. The structure of the resulting 5-(D-g/ycero-diacetoxyethyl)-3-formyl-l-phenylpyrazole 2-acetyl-2-phenylhydrazone (71) was determined by deacetylation followed by oxidation with (a) periodate to a pyrazolaldehyde (72), and (b) permanganate to the known l-phenyl-pyrazole-3,5-dicarboxylic acid (73), as well as by a study of its n.m.r. spectrum, which confirmed the pres-... 

Groups of reportedly photochromic systems which deserve further study include (a) disulfoxides (123,124), (b) hydrazones (125-129), (c) osazones (130-133), (d ) semicarbazones (134-143), (e) stilbene derivatives (144), (/) succinic anhydrides (145-148), and (g) various dyes (149,150). A number of individual compounds also remain unclassified as to their mechanism of photochromic activity. These include o-nitro-benzylidine isonicotinic acid hydrazide (151), 2,3-epoxy-2-ethyl-3-phenyl-1-indanone (152), p-diethyl- and p-dimethyl-aminophenyli-minocamphor (153), brucine salts of bromo- and chloro-nitromethionic acid (154), diphenacyldiphenylmethane (155,156), 2,4,4,6-tetraphenyl-1,4,-dihydropyridine (155,156), 2,4,4,6-3,5-dibenzoyltetrahydropyran (155,156), o-nitrobenzylidenedesoxybenzoin (157), p-nitrobenzylidene-desoxybenzoin (157), N-(3-pyridyl)sydnone (158,159), tetrabenzoyl-ethylene (160), and the oxidation product of 2,4,5-triphenylimidazole (161,162). 

Anhydrides Prepared Directly from the Corresponding Osazones. 31... 

Although Fischer described a lactose phenylosazone anhydride in 1887, little attention was paid to substances of this type until 1935 when Diels and Meyer reported the isolation of monoanhydrides of D-glucose phenylosazone, D-galactose phenylosazone, D-xylose phenylosazone, L-arabinose phenylosazone, lactose phenylosazone, and cellobiose phenylosazone, as well as a dianhydride of maltose phenylosazone, by boiling the corresponding osazones in alcoholic solution with a little sulfuric acid. Because of the apparent identity of the D-glucose phenylosazone anhydride with the 3,6-anhydro-D-glucose phenylosazone of Fischer and Zach, Diels and Meyer formulated these compounds as 3,6-anhydrides. 

D-glucose phenylosazone anhydride from 3,6-anhydro-n-glucose phenyl-osazone (XVI) in the following manner. In support of this view it is... 

In addition, it has been shown that Diels D-glucose phenylosazone anhydride is not identical with 3,6-anhydro-D-glucose phenylosazone for although the osazones are very similar, the diacetates have widely different properties. 

Maltose phenylosazone heptaacetate, on the other hand, yielded two isomeric maltose phenylosazone anhydrides " on deacetylation, both of which gave rise to pentaacetates like the other disaccharide anhydro-osazones, their precise structures are not known. It may be recalled that Diels and Meyer " isolated a dianhydride of maltose phenylosazone... 

A striking feature in the reactions of osazones is the fact that the two hydrazone residues are nonidentical in their reactivity. The hydrazone residue at C-1 is readily alkylated and acylated, but that at C-2 is not. This behavior has been attributed to chelation of the imino proton of the hydrazone at C-2. Furthermore, among the hydroxyl groups of the sugar residue, the one on C-3 seems to be very reactive, readily undergoing dehydration and, in some cases, inversion this is followed in reactivity by the primary hydroxyl group (on C-6 of hexoses), which readily engages in the formation of 3,6-anhydrides. 

Anhydro-osazones are also obtained when osazones are refluxed with acetic acid thus, di-0-acetyl-3,6-anhydro-n-n6o-hexulose 1-iV -acetyl-phenylosazone (92) is formed, together with the dianhydro-osazone (described on p. 178), from n-aroWwo-hexulose phenylosazone (43) and boiling acetic anhydride. On deacetylation, compound (92) yields Diels anhydro-osazone (90), and (92) can be prepared from the latter by acetylation with boUing acetic anhydride. 

Dianhydro-osazones Having Pyrazole Rings.— Another dianhydro-osazone was obtained as the acetate (96) by the author and coworkers by acetylating phenylosazone (43) with boiling acetic anhydride. On de-O-acetylation with methanolic ammonia, the hexose compound (96) yields the iV-acetyl-dianhydro-osazone (97), from which (96) can be prepared by acetylation. The de-O-acetylated dianhydro-osazone (97) was... 

For many years the precise structures of some of the products obtained from reaction of sugars with phenylhydrazine have been the subject of much discussion. Reaction of D-mannose phenyl-hydrazone with acetic anhydride in pyridine yields D-ara6fwo-3,4,5,6-tetraacetoxyl-l-phenylazo-1-hexene. The n.m.r. spectrum of this compound clearly establishes its structure. Acyclic structures have similarly been assigned to various phenylhydrazones and osazones. The work of Wolfrom and his co-workers perhaps best illustrates the kind of approach that has been adopted. The n.m.r. spectrum of o-lyxohexose phenylosazone was measured in dimethyl sulphoxide. The three possible structures of the osazone (44, 45, 46) were considered in terms of the spectrum. 

Formation of Pyrazoles from Bis(hydrazones).—Mesoxaldehyde bis(phenylhydrazone) (193), obtained by periodate oxidation of saccharide osazones (192) is readily cyclized in the presence of acids to give l-phenyl-4-phenylazo-pyrazole (195).162 365 Hexulose phenylosazones (192) are also disproportionaled in the presence of acidic salts of carbonyl reagents, such as hydroxylamine hydrochloride, to give l-phenyl-4-phenylazo-pyrazolin-5-one (196). The reaction probably proceeds via mesoxalic acid 1,2-bis(phenylhydrazone) (194).365 The hydroxalkyl derivatives of 196 are produced from dehydroascorbic acid bis(phenylhydrazone) by treatment with base to open the lactone ring and permit the conversion of 197 to 199.351,366 Another type of pyrazole that is formed by dehydrating osazones with acetic anhydride is discussed later under anhydroosazones (see Schemes 45,53). 

Lactose forms a phenylhydrazone, osazone, and osone. The composition of these substances indicates that lactose contains one free carbonyl group. It is an anhydride of dextrose and galactose, in which one carbonyl group is involved in the union of the molecules, and one is free. The structure of the products formed on oxidizing lactose indicates that the free carbonyl group is in that part of the molecule which yields dextrose on hydrolysis. 

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